In the manufacture of tubular products such as knit hosiery, it is generally necessary to close one end of the tubular structure to form the toe end of the finished product. (For purposes of this application, the term "hosiery" is meant in its broadest sense, and is intended to encompass all types of hosiery articles such as socks, ladies stockings, and the like.) Hosiery articles are conventionally manufactured on either single or double-cylinder circular knitting machines. This operation is typically performed by sewing opposite sides of the open end of the tubular structure together to form a toe pocket of the hosiery article. In some varieties of hosiery, both of the opposite sides of the tubular structure are substantially the same length, so that the toe seam is located on the end of the finished product. In this way, when the hosiery article is positioned on a wearer's foot, the seam is located proximate the ends of the wearer's toes. This construction is primarily used in the manufacture of ladies' sheer hosiery.
In many cases, however, it is desired to have the seam located other than at the ends of the toes, and/or it is also desired to have a structure which more closely corresponds to the three-dimensional shape of a wearer's foot. In such embodiments, one side of the tubular structure is knit so as to have a greater dimension than the opposite side of the tubular structure. This is usually achieved by knitting a tubular structure in a circular fashion, then where extra material is desired, knitting in a reciprocating fashion to provide additional knit courses on one side of the tubular structure. For example, reciprocation is often performed at two spaced-apart regions on one side of the tubular structure, to form a heel pocket and a toe pocket for the wearer's heel and toes, respectively. Because of the extra knit courses formed on one side of the knit structure, when opposite sides of the tubular structure are subsequently joined together to form a closed toe end, the toe-forming seam is positioned on one side (e.g. the top) of the finished stocking. In this way, the toe portion of the stocking can be manufactured to closely follow the contours of the human foot, and the seam can be located at a position where it is unlikely to cause irritation to the wearer's foot when the stocking is worn.
In many sock manufacturing operations, the tubular structures are knit, then transferred to a centralized toe-closing area. Each sock is manually placed by an operator onto a turner which turns the sock inside out. Each sock is then manually placed on a high speed sewing machine which sews the toe together. When placing the sock on the sewing machine, the operator must manually line up the opposite sides of the tubular structure such that the "corners" (formed where the circular knitting stops and the reciprocating knitting starts) are properly oriented to form a properly-shaped pocket and the ends of the opposite sides of the tubular structure are aligned relative to each other. The toe is then seamed closed, and the sock is then turned either manually or by the sewing machine so that the sock is right side out.
Another commercially-utilized method for closing the toes of articles of hosiery involves using a dual bed knitting machine (i.e. one having both a cylinder and a dial) and transferring the last stitch onto the dial. The dial folds in half so that the toe opening is properly aligned for seaming, and the sock is off-loaded from the machine while the stitch is still attached and the opening sewn closed. Some disadvantages with this process are that it requires new machines (i.e., it cannot be done on existing machines), and the purchase price, maintenance, and upkeep costs are generally more expensive than with a standard machine.
Another method used to manufacture socks involves knitting a shaped toe portion on the machine by starting the knitting process at the toe portion rather than at the cuff in the conventional manner. However, this method results in raveling being experienced at the cuff portion, which typically necessitates the provision of an extra band of knitting at the top of the sock. As a result, socks produced in this manner can have an uncomfortable fit which is not smooth. In addition, the machines are generally more expensive than the conventional machines and can be more expensive to maintain. Furthermore, the socks produced by this method have a toe seam on the outside of the sock, which can be aesthetically unappealing.
Because most toe closing operations typically require removal of the tubular structure from the knitting machine, alignment of opposite sides of the structure at the open end and sewing, they are generally relatively labor intensive, and therefore can represent a significant factor in the manufacturing cost of stockings. Furthermore, the toe seaming step, due in part to its labor intensiveness, provides the opportunity for the creation of defects (e.g. by the improper alignment of the opposite sides of the open end of the tubular structure), which can lead to the formation of "seconds" which in turn cannot be sold at the same price as first quality items.
Because circular weft knit fabrics unravel from the last portion knitted, stockings are generally knit starting with the cuff and ending at the toe. A non-raveling region or "clip` is therefore typically knit to the open end of the toe portion so that the open end will be sufficiently stable to allow for the toe closing operation.
Examples of prior attempts to automate the process of closing the ends of stockings are described in patents as follows:
U.S. Pat. No. 2,926,513 to Tew describes a method of closing a toe of a stocking, where the machine engaged in continuous circular knitting is converted to reciprocating knitting. During the reciprocating knitting, certain of the needles are disengaged while the remaining needles continue the knitting operation. Continuous circular knitting is resumed as all needles are engaged for the knitting operation and the toe portion is completed. The tubular foot portion is manually folded flat, with care being taken to ensure the gores of the toe pocket are in registration and the opening is seamed closed.
U.S. Pat. No. 3,800,559 to Fecker describes a method for closing the toes of stockings on conventional circular knitting machines. A toe-closing thread is knit into the toe end of a tubular mesh. The mesh is then cast off the needles of a circular knitting machine and the closing thread is pulled or partially drawn out of the mesh, causing the mesh to be constricted, thereby closing the toe. The closing thread is then knotted to prevent withdrawal of the thread.
U.S. Pat. No. 4,014,186 to Ferraguti describes a method for forming a closed end of a tubular knit sock on a circular knitting machine. Two annular tubular layers are formed as continuations of the tubular knit fabric at separate stages by needles operating in the same cylinder of the machine. The loops at the free edge of the inner layer are held on a support arranged in a circle and the free edge of the inner layer is held on support members arranged in a circle. The free edge of the outer layer is held by the needles until a relative rotation of at least 180 degrees between the circle of support members and the cylinder has been effected. The loops held onto the support members are transferred to the needles of the cylinder, and a final few rows are knit before the fabric is removed from the needles to thereby close the end of the tubular knit fabric.
U.S. Pat. No. 4,958,507 to Allaire et al. describes a method for closing the toe of a double-layered sock. A first course knit by needles corresponding to the end of the tip of a first layer is transferred onto a central transfer plate of a machine where the sock is held. Knitting of the first layer continues from the tip to the mock-up edges. Then knitting is continued on the mock-up edges of the second layer to the tip, the knit tubular structure being suspended by one circular end from the central transfer plate and by the other circular end from the needle cylinder in the course of work, shaping the two concentric layers within each other. The initial course in standby on the plate is transferred to the needles of the cylinder to join the two layers together, and the toe is joined together by knitting.
An additional alternative which has been proposed involves adapting small linking machines to become knitting machines. The stocking is removed from the needles by a split dial and linked onto the knitting machine. While this method can provide satisfactory end closure without operator intervention, many types of existing equipment are not readily adaptable to this conversion. Also, substantial costs are involved in converting the equipment resulting in additional maintenance.
Therefore, a need exists for a method of closing the ends of tubular articles, and in particular, for closing the ends of items of hosiery, which can be performed with minimal labor input and using conventional equipment.